1. Field of the Invention:
The present invention relates to an electric actuating motor with a gear unit for use in a motor vehicle. The motor includes a shaft rotatably supported in a housing, and the shaft includes a shaft end section arranged outside of the housing, with a first toothed part which meshes with a second toothed part supported in a gear unit housing.
Such electric motors are utilized especially for electrical adjustment of, for example, a motor vehicle seat, a window lifting mechanism or in connection with belt transmitter mechanisms. In known electromotors, the shaft end section projects freely from the motor housing before assembly of the actuating motor and gear unit, making it possible for the shaft end to be damaged during transport if the motor is accidentally dropped. This can lead to an undesirable whipping of the shaft or damage to the first toothed part.
2. Background of the Invention:
Accordingly, it is an object of the present invention to considerably reduce the threat of damage to an actuating motor of the above-mentioned type prior to assembly with the gear unit.
Pursuant to this object, and others which will become apparent hereafter, one aspect of the present invention resides in attaching a bearing shield at the motor housing with a bearing shield attachment flange for connection with the motor housing. A bearing shield side wall includes a through opening for the second toothed part and embraces the shaft end section. A bearing shield end wall is provided on the side of the first toothed part facing away from the motor housing in whose region a bearing area for the shaft end section is configured.
In the invention, the electric actuating motor is initially provided with the bearing shield. The shock loads occurring during transportation are for the most part kept away from the sensitive shaft, as well as from the first toothed part, since these shocks can be directly transmitted by the bearing shield to the motor housing. An additional advantage of this embodiment of the invention resides in that the first toothed part is supported on both sides and thus is in a mechanically more stable position.
In a further embodiment of the invention, the external peripheral surface of the side wall is cylindrical. During the course of assembly of the actuating motor with the housing, the motor need merely be slid into a corresponding cylindrical receiving opening of the gear unit housing, thereby providing the advantage of an accurate positioning in the gear unit housing. It is also possible to actually displace the actuating motor in the gear unit housing opening for a precise mutual positional adjustment of the first and the second toothed parts in order to assure satisfactory operation of the gear unit.
Alternatively, the external peripheral surface of the side wall can also be designed to taper conically towards the end wall. This embodiment is principally advantageous if a final axial adjustment is not required. The advantage of this arrangement lies in that a mechanically stable connection which is free of play between the motor and gear unit is assured because of the conical seat in a correspondingly conical housing receiving opening, even if the conical surfaces should include manufacturing inaccuracies.
In yet another embodiment an axial play adjustment element is provided for elimination of excessive axial play of the shaft. This adjustment element is supported at the end wall and engages at the shaft end section. An adjustment screw is the preferred structure of the adjusting element. The adjustment or the elimination of axial play is important mainly if, according to a preferred embodiment of the invention, the first toothed part is a worm which co-acts with a worm wheel which constitutes the second toothed part. During operation, the shaft is then stressed in one or the other axial direction, depending on the direction of rotation. This stress change, which occurs when the direction of rotation is reversed, can result in impact shock on the shaft in the axial direction in the case where axial play of the shaft is excessive, thus, leading to increased wear and noise generation. This axial play can be eliminated by the axial play adjustment element.
Preferably, the gear unit housing is attachable directly at the bearing shield. For this purpose, the attachment flange can be formed by an annular flange projecting radially outwards from the side wall, with threading-in apertures for the gear unit housing attachment bolts.